code: def test_multithreading_neighbor_loader(spawn_context):
      loader = NeighborLoader(
          data=Data(x=torch.randn(1, 1)),
          num_neighbors=[-1],
          batch_size=1,
          num_workers=2,
          worker_init_fn=init_fn,
      )
  
      with loader.enable_multithreading(2):
          loader._get_iterator()
  
file_path: pytorch_geometric/test/loader/test_mixin.py
imports: import subprocess
  from time import sleep
  import pytest
  import torch
  from torch_geometric.data import Data
  from torch_geometric.loader import NeighborLoader
  from torch_geometric.testing import onlyLinux, onlyNeighborSampler
label_desc: Use image node_id 3 for calling a global function with example usage: test_multithreading_neighbor_loader(spawn_context) without return types